Mine were dim and yellow, too. They also only worked on hi beam. Re-wiring them correctly and installing new grounds and lamps did the trick.
Part of the problem was at the dimmer switch where the power comes in for the lights.
Your dash switch may just be gunked up with dirt or rust.
Original gauge clusters are available but you might have to look for a donor dash panel to replace what was cut out.
Removing the switch for cleaning is pretty easy. Do you have a shop manual?
